Question 6754: Omitting One Existing Factor and Multiplying Back

Original question and givens

N begins at 0, F(0)=0!=1, and factorials use exact integer arithmetic, not floating point. n=5, k=4∈[1,n]. Give (n!, product with k omitted once n!/k, k times that product minus n!).

• G001 — N begins at 0, F(0)=0!=1, and factorials use exact integer arithmetic, not floating point. n=5, k=4∈[1,n]. Give (n!, product with k omitted once n!/k, k times that product minus n!).

Definition and scope

Use the original question domain, assumptions and cited MKO definitions. This item has second-context mathematical and bilingual review, with the model, answer and every arithmetic step independently recomputed from the original parameters; the source question remains a candidate.

• mko-factorial

Step-by-step derivation

N includes0;F(0)=1;F(j)=j·F(j−1)

exact integer products,not floating values or a permutation proof

actual factorial:start at F(0)

F(0)=1

actual factorial through factor1 := mul(1, 1)

actual factorial through factor1 = 1

actual factorial through factor2 := mul(1, 2)

actual factorial through factor2 = 2

actual factorial through factor3 := mul(2, 3)

actual factorial through factor3 = 6

actual factorial through factor4 := mul(6, 4)

actual factorial through factor4 = 24

actual factorial through factor5 := mul(24, 5)

actual factorial through factor5 = 120

single-factor-omitted product := div(120, 4)

single-factor-omitted product = 30

restore omitted factor := mul(4, 30)

restore omitted factor = 120

restored product minus factorial := sub(120, 120)

restored product minus factorial = 0

removed factor k=4;full n!=120

omitted product=30;restoration residual=0

Reverse checks

• S011 · premise_and_result_audit — Check against the original data and this step's premises; a one-way implication is not an equivalence.
• S010 · premise_and_result_audit — Recompute restored product minus factorial with exact rational arithmetic, not rounded decimals.
• S009 · premise_and_result_audit — Recompute restore omitted factor with exact rational arithmetic, not rounded decimals.
• S008 · premise_and_result_audit — Recompute single-factor-omitted product with exact rational arithmetic, not rounded decimals.
• S007 · premise_and_result_audit — Recompute actual factorial through factor5 with exact rational arithmetic, not rounded decimals.
• S006 · premise_and_result_audit — Recompute actual factorial through factor4 with exact rational arithmetic, not rounded decimals.
• S005 · premise_and_result_audit — Recompute actual factorial through factor3 with exact rational arithmetic, not rounded decimals.
• S004 · premise_and_result_audit — Recompute actual factorial through factor2 with exact rational arithmetic, not rounded decimals.
• S003 · premise_and_result_audit — Recompute actual factorial through factor1 with exact rational arithmetic, not rounded decimals.
• S002 · premise_and_result_audit — Check against the original data and this step's premises; a one-way implication is not an equivalence.
• S001 · premise_and_result_audit — Check against the original data and this step's premises; a one-way implication is not an equivalence.

Result

(120, 30, 0)

The full substitutions and premise checks give the original answer; source identity,format and status are unchanged.

This question review and source binding

Review date: 2026-10-26

Original questions, answers, step expressions, numeric ASTs and historical records are retained. Source candidate labels remain historical and are not overwritten as formal proof.